Decelerating device for firearms with telescopic bolts



F. P. REED June 21, 1960 DECELERATING DEVICE FOR FIREARMS WITH TELESCOPIC BOLTS Filed March 4, 1959 3 Sheets-Sheet 1 INVENTOR. Frad:.ri':k. F Rcaa BY M. flow; a-aflw F. P. REED June 21, 1960 DECELERATING DEVICE FOR FIREARMS WITH TELESCOPIC BOLTS Filed March 4, 1959 3 Sheets-Sheet 2 INVENTOR. Frederick .P .E'cc: 15

BY 1/ 9304 9 4. a. waif F. P. REED June 21, 1960 DECELERATING DEVICE FOR FIREARMS WITH TELESCOPIC BOLTS Filed March 4, 1959 3 Sheets-Sheet 3 INVENTOR. Freaa-ni ck P -E'cn: 5

BY 2%. Mi; *Q V I a 2,941,449 1C6 l 'a'lerited June 21, 1960 DECELERATING DEVICE FOR FIREARMS WITH TELESCOPIC BOLTS Frederick P. Reed, Ludlow, Mass., assignor to the United States of America as represented by the Secretary of the Army .Filed Mar. 4, 1959, Ser. No. 797,317

1 Claim. (Cl. 89-185) (Granted under Title 35, US. Code (1952), see. 266) with the barrel whenthe bolt is stopped .thereagainst inv battery position. The reasonsfor this inaccuracy are that the shock'of impact sets up vibrations in the barrel which afiects the courses of the projectiles when 'leavingthe muzzle thereof and that the shock of inertia variably shifts the propellant and/ or the projectiles in the cartridges to produce irregular flight characteristics. I

-In those firearms using single-piece bolts, the means for locking thebolt in battery position often times serve also to decelerate the bolts. But in the pastthere has not been provided any adequate means for deceleratingthose bolts of telescopic type wherein the bolt is stopped in battery position by the engagement thereof with the bars rel and then is rotated to lock position by movement of a carrier relative to the bolt and no means have heretofore been provided for replacing the engaging surfaces which are worn or mutilated by the deceleration without having to replace major components as the bolt, barrel or receiver. t j

. It is, therefore, an object of this invention to provide means for decelerating telescopic-type bolts when going into battery position.

It is another object of this invention to provide in the barrel assembly of a firearm having a telescopic-type bolt a replaceable decelerator member which is engagea-ble by the bolt when going into battery position for gradually decelerating the .bolt by uniformly converting the longi: tudinal movement thereof to a decelerated helical movement into battery position. 7

It is still another object of this invention to provide for firearms provided with bolts of stated type which have bayonet lugs disposed for rotating engagement with, cooperating bayonet lugs in the barrel assembly a decele-,; rator member separably mounted in the barrel assembly relative to the bayonet lugs therein for uniformly converting the longitudinal movement-of the bolt to helical movement and the helical movement to rotary movement for a gradual deceleration of the bolt.

it is a further object of this invention to provide a decelerator which maybe. fabricated from material different from that of the bolt and barrel so that the deformativ'e forces produced by the impact and engagement between the bolt and barrel assembly will .be borne ,by-

such decelerator whereby defective engaging relationship between the bolt and barrel during deceleration may be easily repaired by replacing the decelerator and thereby save having to replace the more expensive barrel or bolt.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a longitudinally cross-sectioned side view of a firearm receiver showing the bolt in locked extended position and clear of the barrel assembly;

Fig. 2 is a view similar to Fig. 1 but showing the bolt in locked battery position; i

Fig. 3 is a partially cross-sectioned top view of the receiver showing the position of the bolt at moment of impact with the decelerator;

Fig. 4 is a view similar to Fig. 3 but showing the bolt helically actuated by the decelerator to battery position;

Fig. 5 is a view along line 5-5 of Fig. 1;

Fig. 6 is a view along line 66 of Fig. 2;

Fig. 7 is a view along line 77 of Fig. 3;

Fig. 8 is a perspective exploded view of the barrel assembly;

Fig. 9 is a schematic view showing the relationship of the bolt assembly and decelerator when the bolt assembly is in recoil position and the bolt is in full extended posi-' tion in the carrier;

Fig. 10 is a view similar to Fig. 9 but showing the relationships of the follower with the cam slot and the bayonet lugs on the bolt with the helical cam surfaces in the decelerator during counterrecoil stroke of the bolt assembly when the bolt is in the locked extended posi-' tion; and

Fig. 11 is a view similar to Figs. 9 and 10 but showing the relationships of the follower and cam slot and the bayonet lugs on the bolt with the helical surfaces in the decelerator when the bolt has been actuated thereby to battery position.

Shownin the figures is a firearm 12 provided with a cylindrical receiver 14 in which there is slidingly mounted:

a bolt assembly 16 which is reciprocable between a recoil and a battery position responsive to forces produced by the discharge of cartridges in the firearm. Bolt assembly 16 is of two-piece type and includes a nonrotatable carrier 18, which is energized for such reciprocation by conventional gas actuated means (not shown), and a bolt 20 telescopically mounted therein.

Provided in carrier 18 is a cam slot 22 which slidingly engages a follower 24 on bolt 20 for rotating the bolt in' a clockwise direction to a locked battery position when telescoped into the carrier and in a counterclockwise direc tion to an unlocked battery position when bolt 20 extends from carrier 18. Bolt 20 is releasably locked against telescoping and against rotary displacement relative to carrier 18 by a transversely actuated lock 26, as hereinafter described. Y

Mounted to the front end of receiver 14 is a barrel assembly 28 which includes a barrel 30, a barrel exten sion 32 and a decelerator 34. Barrel 30 is provided at the breech end'with an external threaded portion 36 of reduced diameter which is terminated forwardly by a shoulder 38. Decelerato'r 34, which is cylindrical in conbarrel. Barrel 30, with decelerator 34 engaged therewith, is threadably mounted to the front end of barrel extension 32 so that the front end, thereof contactsshoulder 38. Decelerator 34 is received by a mating bore 44 provided axially in barrel extension 32 and is thereby v positioned in axialalignment with barrel 30 while an, annular shoulder 46 terminating the rear end of such bore contacts the rear end of the decelerator to maintain such decelerator in abutment with the rear end" of barrel 30 and thereby secured against longitudinal displacement.

Barrel extension 32 is fixedly mounted within thefront end of: receiver-14 by cooperating bayonet lugs- 45 and a screw 47 extends radially through the receiver and barrel extension into barrel 30 to secure'barrel assembly 28 against longitudinal and rotary displacement in the reeeiver.

Pro'vided on the front-end of bolt is a head portion 48 which is extendable through suitable openings in barrel extension 32 and decelerator 34 to chamber a cartridge in barrel 30 and close the breech end thereof when the bolt is in the battery position. Extending radially from head portion 48 are aplurality of diametricallydisposed pairs of bayonet lugs 50 which are longitudinally spaced thereon and which are rotatable alternately between matingpairs of bayonet lugs 52 in barrel extension 32, when bolt 20 goes into battery position, for releasably securing the bolt against longitudinal displacement in the lock position. The bayonet lugs 50 are positioned when bolt 20 is in the unlocked battery position to pass longitudinally through the bayonet lugs 52.

The front pair of the bayonet lugs 50 are engageable with cam surfaces 54, which are formed by a pain of diametrically disposed recesses 56 extending forwardly from the rearend of decelerator 34, just before bolt 20 reaches battery position. The cam surfaces. 54-extend helically forward and in a clockwise direction from the rear endof decelerator 34 so that bolt 20is spun helically in a forward and-clockwise direction to gradually decelerate the forward-movement thereof by converting the longitudinal movement thereof to helical movement. The left wall of cam slot 22 is curved outwardly, rearwardly from the front end thereof, to form a pocket 58- Which-receives follower 24 during counterrecoil movement of bolt assembly 16, as hereinafter described, and therebyprovides forthe helical displacement of follower 24 when bolt 20is helically spun by the engagement of; V

the bayonet lugs 50 with the cam surfaces 54.

The corners of the bayonet lugs 50 which engage the cam surfaces 54 are provided with radii, as noted at 60, td form a cylindrical surface for contact with the cam surfaces 54 and sobroaden the impact area of bolt 20 with barrel assembly 28 and increase the sliding relationship therebetween. The front corners of the lugs 52', around which the bayonetlugs 50 are moved, are chamfered, as noted at 62, to provide clearances for the passage of the bayonet lugs 50.

The-cam surfaces 54 are disposed so that the bayo'net lugs 50 are delivered thereby directlybetween the bayonet lugs 52; as is best shown in Fig. 4, for a uniform transition from the helical displacement of bolt 20 by'the cam surfaces to the subsequent rotarydisplacement of the bayonet lugs 50. The rotary displacement of bolt '20 is effected by the cooperation of the sliding engagement of the bayonet lugs 50 and 52 and the engagement of follower 24 in cam slot 22.

Look 26, which releasably preventsbolt 20 from telescoping, is slidingly disposed for transversal movement through carrier 18 adjacent the rear end: of the bolt when adjacent the extended position thereof in the carrier. Lock--26- is slidingly received by a segmental recess 64 formed-in the top, rear-end of-bolt 20 'by'a laterally disposed chordal portion 66 which extendsforwardly from the rear end of the bolt and which isterminated forwardly by a vertically disposed face portion 68. Look alignedgwithbolt 20 which therefore is blocked against telescoping into carrier 18 and thevbottorn side of the look is. irnengagernent with a chordal portion 66 so ,as to the mass of the carrier is gradually united with the massated to the unlock position, during the counterrecoil movement of bolt assembly 16, by the engagement of the end thereof with a cam 72 (Fig. 3) in the right side of receiver 14 and to the lock position, during recoil movement, by a cam 74 in the left side of the receiver. The cams 72 and 74 are disposed so as to actuate lock 26 between, the lock and unlock positions thereof when the front bayonet lugs 50 are immediately rearward of engagement with the cam surfaces 54.

Thus, when bolt 20 is in locked battery position, wherein the bayonet lugs 50 and 52 are in engagement, and a cartridge is discharged in barrel 30, carrier 18 is energized for cyclic reciprocation in receiver 14. During the recoil stroke of carrier 18, cam slot 22 is moved along follower 24 and thereby rotates bolt 20 to the unlock position. As cam slot 22 is developed to rotate bolt 20 counterclockwise to the unlocking position, it is the right wall of the cam slot which slidingly engages follower 24 to rotate bolt 20 during the recoil stroke of carrier. Follower 24 is directed by such right wall of cam slot 22 to the front portion thereof, forwardly of pocket 58 and thereby the bolt is correctly positioned for the engagement of chordal portion 66 with the underside of lock 26 and for the passage of the bayonet lugs 50 past the bayonet lugs 52. When follower 24 contacts the front end of cam slot 22, bolt 20 is picked up thereby to travel with carrier 18 to recoil position. Immediately after the pickup of bolt 20 by carrier 18 lock 26 is actu ated to the lock position and thereby the bolt is releasably blocked against telescoping into the carrier and against rotary displacement. A dwell period is provided between the full extended position of bolt 20 in carrier- 18', as shown in Fig. 9, and the position wherein the boltis in engagement with lock 26 during counterrecoil stroke of the carrier, as shown in Fig. 10. This dwell period is such that when bolt 20 is in engagement with lock 26, follower 24- is positioned in pocket 58 and thereby free'to be helically actuatable when the bolt engagesdecelerator- 34.

As bolt 20 approaches battery position towards the end of such counterrecoil stroke lock 26 is actuated to the unlock position thereof so as to free the bolt for longitudinal and rotary movement relative to carrier 18 immediately before the front pair of the bayonet lugs 50' are led directly by the cam surfaces into engagement with thebayonet lugs 52 so that the helical movement of bolt- 20 is uniformly translated through the cooperation of camslot- 2'2 with follower 24 to rotary-movementascarrier 18 continues forwardly relative to the bolt.

It is readily seen that whenlock 26 is in the unlock position and follower 24 is being rotated across cam slot 22 from pocket 58, bolt 20 is virtually free of the mass of'carrier l 8 when the bolt contacts barrel assembly 28, to reduce the impact of bolt assembly 16 therewith, and

impact ofbolt assembly 16 with barrel assembly 28 is.

reduced so that little, if any, adverse effect is produced to affect the accuracy of firearm 12.

Moreover, when decelerator 34 becomes worn or mutilated from usage, it is easily replaced by removing barrel assembly 28 from receiver 14 and then unscrewing barrel 30 from barrel extension 32 which frees the decelerator 'for removal and replacement so that firearm 12 is easily repaired without having to replace any major components.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claim is intended to include such variations.

I claim:

In a firearm including a receiver, the combination of a barrel assembly provided with a decelerator replaceably assembled to the breech thereof, a telescopic bolt assembly slidingly disposed in the receiver for reciprocation to and from a battery position, said bolt assembly including a carrier and a bolt telescopically disposed therein, a cam slot disposed in said carrier for cooperation with a follower in said bolt for rotating said bolt to and from a lock position during longitudinal movement of said carrier relative thereto, cam means disposed on said decelerator for engagement by said bolt when adjacent the battery position to convert the longi- .8 tudinal movement of said bolt assembly to helical movement of said bolt, a pocket portion extending from said cam slot and disposed therein to provide clearance for helical movement of said follower when said bolt is helically actuated by the engagement thereof with said decelerator, lock means for immovably connecting said carnier to said bolt to prevent the telescoping thereof into said carrier, and cam means in the receiver for actuating said lock means to disconnect said carrier from said bolt and thereby release the mass of said carrier from that of said bolt when said follower is actuated into said clearance portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,717,535 Taylor Sept. 13, 1955 2,775,920 Dixon et a1. Jan. 1, 1957 FOREIGN PATENTS 707,369 Germany June 20, 1941 708,197 Germany July 15, 1941 

